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Robust design of power system stabilizers for damping power system oscillations

(電力系統の振動抑制に対する系統制御器のロバスト設計)

氏名 Hardiansyah
学位の種類 博士(工学)
学位記番号 博甲第316号
学位授与の日付 平成16年6月30日
学位論文題目 Robust design of power system stabilizers for damping power system oscillations (電力系統の振動抑制に対する系統制御器のロバスト設計)
論文審査委員
 主査 教授 入澤 壽逸
 副査 教授 近藤 正示
 副査 助教授 大石 潔
 副査 助教授 原田 信弘
 副査 助教授 野口 敏彦

平成16(2004)年度博士論文題名一覧] [博士論文題名一覧]に戻る.

Contents

Abstract p.1
List of Figures p.2
List of Tables p.3
1. Introduction p.1
 1.1. Background and motication p.1
 1.2. Organization of this dissertation p.5
2. Dynamic Models for Small Signal Stability Analysis p.6
 2.1. Background p.6
 2.2. General approach p.7
 2.3. Small perturbation dynamic model of the system p.9
 2.4. Systems investigated p.11
 2.5. Single-machine infinite-bus(SMIB) system p.11
 2.6. Multi-machine system p.15
 2.7. Power system stabilizer(PSS) p.18
 2.8. Conclusions p.20
3. Reduced-Order H∞ Power System Stabilizer Design p.21
 3.1. Problem statements p.21
 3.2. Reduced-order model formulation p.22
 3.3. The bilinear transformation p.24
 3.4. Low order controller design p.25
 3.5. Application to power system stabilizer design p.27
 3.6. Simulation results p.29
 3.7. Conclusions p.34
4. LMI-Based Robust H2 Controller Design p.35
 4.1. Introduction of linear matrix inequality(LMI) p.35
 4.2. Proposed H2 controller design p.36
 4.3. Simulation results p.38
 4.3.1. A single-machine infinite-bus system p.38
 4.3.2. A 3-machine 9-bus system p.40
 4.4. Conclusions p.49
5. LMI-Based Robust H2 Control Design with Regional Pole Constraints p.50
 5.1. LMI-based H2 controller design p.50
 5.2. LMI formulation for regional pole constraints p.51
 5.3. Robust H2 control with regionalpole constraints p.53
 5.4. Simulation results p.54
 5.4.1. A single-machine infinite-bus system p.54
 5.4.2. A 3-machine 9-bus system p.58
 5.5. Conclusions p.64
6. LMI-Based Mixed H2/H∞ Controller Design with Regional Pole Constraints p.65
 6.1. LMI formulation for mixed H2/H∞ performance p.65
 6.2. Mixed H2/H∞ controller with regional pole constraints p.67
 6.3. Simulation results p.68
 6.3.1. A single-machine infinite-bus system p.68
 6.3.2. A 3-machine 9-bus system p.74
 6.4. Conclusions p.82
7. Conclusions and Further Research p.83
 7.1. Conclusions p.83
 7.2. Further reserch p.84

Acknowledgments p.85

References p.86

Power systems are usually large nonlinear systems, which are often subject to low frequency oscillations when working under some adverse loading conditions. To enhance system damping, the generators are equipped with power system stabilizers (PSSs) that provide supplementary feedback stabilizing signals in the excitation systems. PSSs enhance the power system stability limit by enhancing the system damping of low frequency oscillations associated with the electromechanical modes. Conventional power system stabilizer (CPSS) of the lead-lag compensation type has been adopted by most utility companies because of their simple structure, flexibility and easy of implementation. Unfortunately, the major disadvantage of the CPSS design method is that it does not guarantee system stability under varying operating conditions.
In today's practical power systems, the small-signal stability problem is usually one of insufficient damping of system oscillations. The details of mathematical models required for the analysis of small-signal stability for both single-machine infinite-bus (SMIB) and multi-machine power systems are presented in Chapter 2. The mathematical models are in the state-space form, thereby making the application of linear analysis possible. As has been demonstrated, for SMIB system is unstable and multi-machine system has lightly damped mode under small perturbations and require additional stabilizing control from the power system stabilizers, the design of which will be treated in the following chapters.
A reduced-order H power system stabilizer (HPSS) design to improve the damping oscillation in power system has been presented in Chapter 3. By solving two algebraic Riccati equations (AREs), then a lower-order dynamic output feedback controller is constructed. The bilinear transformation has been used to deal with the j -axis poles and zeros and to prevent the pole-zero cancellation. The resulting reduced-order controller is guaranteed to stabilize the closed-loop system. Performance of the proposed controller in multi-machine power system has been compared to the conventional PSS (CPSS). The results show that the proposed HPSS is more effective and gives promising result for robustness and stability in damping of low frequency oscillation at different loading conditions.
The design of robust H2 controller for damping oscillations in power systems based on linear matrix inequalities was presented in Chapter 4. The performance evaluation of the proposed stabilizer on SMIB and multi-machine systems shows that this increased robustness could be achieved with reasonable feedback gain magnitudes. Further, in the multi-machine case, the control is decentralized and only locally measured variables are feedback at each generator. Simulation results show that the proposed stabilizers (H2PSS) can effectively enhance the damping of low frequency oscillations and perform better than conventional stabilizers (CPSS).
In Chapter 5, robust H2 control design with regional pole constraints for damping power system oscillations based on linear matrix inequalities were presented. The effectiveness of the proposed stabilizers (H2PSS) on SMIB and multi-machine system are shown for a variety of disturbances and operating conditions.
In Chapter 6, the design of mixed H2/H∞ controller with regional pole constraints for damping power system oscillations has been proposed. The required state feedback gain has been obtained by solving a linear matrix inequality (LMI) feasibility problem that robustly assigns the closed-loop poles in a prescribed LMI region. The performance of the proposed stabilizer on a SMIB and a multi-machine power system are seen to be robust over a wide range of operating conditions. Finally, simulation results show the effectiveness and robustness of the proposed stabilizer to enhance the damping of low frequency oscillations.

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